A large body of clinical research shows that web-based and phone applications can treat depression and anxiety. These applications — called behavioral intervention technologies (B.I.T.s) — differ in style from traditional face-to-face forms of therapy, but the aim is the same: to help people understand their difficulties, and take steps to reduce symptoms.

To do this, most B.I.T.s include straightforward steps for improved wellbeing, as well as interactive features, which build cognitive and behavioral skills that identify and challenge negative thinking patterns.

To be effective, B.I.T.s require repeated use over a number of weeks — an obstacle because many people with depression or anxiety have trouble staying engaged long enough to make substantial improvements. But even a small amount of support from a coach or therapist via phone calls or messaging, can lead to improvements similar to that of face-to-face psychological treatments.

Therapist or coach-supported B.I.T.s have been so successful that many countries have integrated such apps into their health care systems, including Australia, the Netherlands and Britain.

The question, then, is no longer whether apps are effective, but, rather how best to design them.

At Northwestern University’s Center for Behavioral Intervention Technologies, psychologists, physicians and software engineers create products that help people manage their mental health. For example, our Daily Feats app provides checklists with successive goals to activate people who are depressed. Another app, Aspire, helps people identify personal strengths and values, and prompts them to begin acting with a greater sense of meaning and purpose. The Thought Challenger app uses cognitive behavioral techniques to challenge negative thinking.

Of course, B.I.T.s are still an emerging field, and they are not a panacea. But as nearly 80 percent of Americans with mental health disorders receive no mental health care whatsoever, apps could provide cost-effective services more broadly.

The big challenge in the U.S. will be how to provide people with coverage, since our health care system pays on a fee-for-service basis, and preventive care is often not covered by insurance.

Another complication is that consumers don’t have reliable information about the quality of the thousands of apps. Countries that are implementing B.I.T.s provide guidelines for only some of what is available in today’s marketplace. What's more, certification requirements for B.I.T. coaches have not been defined.

When implemented correctly, though, B.I.T.s can significantly broaden the availability of mental health care. The technology, however, should not be greeted as a replacement for more traditional treatments, which are severely under-funded but still necessary for many.

- David C. Mohr is a professor of preventive and behavioral medicine and the director of Northwestern University's Center for Behavioral Intervention Technologies